JP2002153778A - Spindle for electrostatic coating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spindle suitable for an electrostatic coating machine using a water soluble paint and excellent corrosion resistance and bearing durability in use at the time of high speed rotation. SOLUTION: In the spindle for the electrostatic coating machine having a main shaft 2, a journal bearing part 4 for supporting the main shaft 2 statically in a radial direction with respect to a bearing sleeve 37 and a housing 39, thrust bearing parts 40 and 44 for supporting the main shaft 2 statically in a thrust direction with respect to bearing sleeves 37 and 38 and housings 39, 40, bearing sleeves 37 and 38 constituting both bearing arts 42-44 and the housing 39-40 externally fitted to the bearing sleeves 37 and 38 and provided with an atomizing head for atomizing a paint attached to one end part of the main shaft 2, the bearing sleeves 37 and 38 are formed of a fragile material such as graphite or the like having self-lubricity and the housings 39-41 are formed of a metal material such as stainless steel or the like having corrosion resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle for an electrostatic coating machine, and more particularly, to a spindle for an electrostatic coating machine.
The present invention relates to a spindle for an electrostatic coating machine in which a spindle to which a paint jetting head is attached is supported by a static pressure gas bearing in a non-contact manner.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example of a spindle for an electrostatic coating machine using an air turbine as a driving means. The spindle 1 has a plurality of recesses 4 in the outer diameter of the thrust plate 3 of the main shaft 2.
To form a driving turbine section 6, and a turbine nozzle 5 disposed at a portion facing the recess 4.
The main shaft 2 is rotated by spraying compressed air from the nozzle, and an atomizing head for atomizing paint is attached to one end of the main shaft 2 (not shown).

A main shaft 2 and a thrust plate 3 integrally connected to the main shaft 2 are provided with bearing sleeves 7 and 8 and first and second bearings.
Journal bearings 12 and thrust bearings 13 and 14 formed in the second housings 9 and 10 rotatably support the bearing sleeves 7 and 8 and the first and second housings 9 and 10 in a non-contact manner. ing.

The journal bearing portion 12 and the thrust bearing portion 13 are constructed by shrink-fitting the bearing sleeve 7 to the substantially cylindrical first housing 9 and internally fitting the sleeve 7 by appropriate means such as press-fitting or bonding. Similarly, the thrust bearing portion 14 is configured by shrink-fitting the bearing sleeve 8 into the circular lid-shaped second housing 10 and fitting the sleeve 8 by appropriate means such as press-fitting or bonding.

The bearing sleeves 7 and 8 are formed of a general copper-based alloy as an air bearing material, and a plurality of fine journal bearing nozzles 15 and 16 and thrust bearing nozzles 17 and 18 are disposed on both of them. Have been.

[0006] Between the first and second housings 9 and 10,
A ring-shaped third housing 11 is interposed, and the first to third housings 9 to 11 are integrally assembled by fastening means such as bolts. These first to third housings 9 to 11 (hereinafter, simply referred to as “housings” when collectively referring to the first to third housings) are provided within a resin coating machine case 19 within an elastic member 20 such as an O-ring. The storage is arranged via. The housings 9 to 11 are generally made of a light metal such as an aluminum alloy for the purpose of weight reduction.

The journal bearing nozzles 15, 1 of the bearing sleeves 7, 8 are provided in the first and second housings 9, 10.
6 and thrust bearing nozzles 17, 18 are formed with circumferential grooves 25-27, respectively, and further, air passages 21, 22 are formed with the circumferential grooves 25-27. The third housing 11 has an air passage 22 of the first housing 9 and an air passage 2 of the second housing 10.
3 is formed. Also,
An air supply port 28 communicating with the circumferential groove 26 and the air passage 22 of the first housing 9 is provided in the first housing 9,
An air passage 29 communicating with the air supply port 28 is provided in the coating machine case 19. Further, the third housing 11
A plurality of turbine nozzles 5 open substantially tangentially along the inner circumference at a position facing each recess 4 of the thrust plate 3.
Are formed through.

The compressed air supplied from the air passage 29 of the coating machine case 19 flows from the air supply port 28 of the first housing 9 via the circumferential groove 26 and the air passage 21 to the circumferential groove 25.
And is jetted from the journal bearing nozzles 15 and 16 of the journal bearing portion 12 of the bearing sleeve 7 to the bearing surface,
The journal shaft 12 supports the main shaft 2 in the radial direction.

The compressed air is jetted from the thrust bearing nozzle 17 of the bearing sleeve 7 to the bearing surface of the thrust bearing portion 13 through the circumferential groove 26 of the first housing 9.
Further, the compressed air is also supplied to the circumferential groove 27 from the air passages 22, 24, 23 of the first, third, and second housings 9, 11, 10, and from the thrust bearing nozzle 18 of the bearing sleeve 8 to the thrust. It is ejected to the bearing surface of the bearing portion 14. In this way, the thrust bearing portions 13 and 14 allow the main shaft 2
Are supported in the axial direction.

On the other hand, the compressed air supplied from the air passage 30 of the coating machine case 19 is jetted from the turbine nozzle 5 of the third housing 11 toward the recess 4 of the thrust plate 3 of the main shaft 2 in a substantially tangential direction. . The jetted compressed air gives a rotational force to the main shaft 2 and is discharged to the outside of the spindle 1 from an exhaust port (not shown). An atomizing head (not shown) for atomizing the paint is attached to an end (the left end in the figure) of the main shaft 2 to perform electrostatic coating.

[0011]

In the above-mentioned conventional spindle for an electrostatic coating machine, for the purpose of weight reduction,
In general, the housings 9 to 11 are formed of a light metal such as an aluminum alloy.
A common copper-based alloy is often used as an air bearing material. When the housings 9 to 11 are made of an aluminum alloy and the bearing sleeves 7 and 8 are made of a copper-based alloy, the copper-based alloy has a higher density than the aluminum alloy, so that the housings 9 to 11 and the bearing sleeves 7 and 8 are made. In general, the volume ratio of the housings 9 to 11 to the bearing sleeves 7 and 8 is set to 1 or more in order to reduce the weight of the entire housing assembly formed of

On the other hand, in the recent electrostatic coating, a shift from an organic solvent-based coating, which has been mainly used conventionally, to a water-soluble coating is progressing in view of environmental problems. When this water-soluble paint is used, in the spindle 1 using an aluminum alloy for the housings 9 to 11 as in the related art, the housings 9 to 11 are used.
Has the problem of corrosion. As this corrosion countermeasure,
One of the effective means is to use stainless steel for the housings 9 to 11. However, the material is changed with the conventional structure in which the volume ratio of the housings 9 to 11 to the bearing sleeves 7 and 8 is 1 or more. Then, it is difficult to avoid a large increase in the weight of the entire housing assembly.

Further, there is an increasing demand for high-speed rotation of the spindle 1 for the purpose of improving the coating performance. In particular, in the case of the above-mentioned water-soluble paint, the necessity of high-speed rotation of the spindle 1 is further increased because the viscosity is higher than that of the organic solvent-based paint. With the high-speed rotation of the spindle 1, it is necessary to improve the durability of the bearing part. In this regard, the self-lubricating material is a material that is not easily damaged even if it contacts the bearing part at high speed rotation. Graphite, which has been recently awarded as an excellent air bearing material, may be mentioned.

However, the conventional bearing sleeves 7, 8
Is made of graphite, there is a problem that anodic corrosion occurs on the joint surface with the housings 9 to 11 made of an aluminum alloy. In particular, in the case of an electrostatic coating machine using a water-soluble paint, since it is used in an environment where water is present in the vicinity, the problem of aluminum corrosion is more serious, and aluminum alloy housings 9 to 11 and graphite are used. It is difficult to use the bearing sleeves 7 and 8 in contact with each other.

It is conceivable that the housings 9 to 11 and the bearing sleeves 7 and 8 are made of graphite as a single structure. However, graphite has a small elastic coefficient and is easily affected by deformation due to a chuck during processing. Difficult to process the surface with high precision. In addition, in the electrostatic coating machine, it is necessary to attach and detach the spindle 1 from the coating machine case 19 during maintenance or the like during use. There is a problem that the housings 9 to 11 made of graphite are easily damaged and chipped during handling, including this attaching / detaching operation.

Accordingly, the present invention has been proposed in view of the above problems, and has as its object to be suitable for use in an electrostatic coating machine using a water-soluble paint, and to provide corrosion resistance and high speed rotation. Another object of the present invention is to provide a spindle having excellent bearing durability.

[0017]

According to a first aspect of the present invention, there is provided a bearing having a main shaft, a bearing sleeve for rotatably supporting the main shaft, and a bearing sleeve. A housing externally fitted to the bearing sleeve, and a spindle for an electrostatic coating machine having an atomizing head for atomizing paint at one end of the main shaft, wherein the bearing sleeve is made of a brittle material having a self-lubricating property. The housing is formed of a material, preferably graphite (claim 3), and the housing is formed of a corrosion-resistant metal material, preferably stainless steel (claim 4).

According to a second aspect of the present invention, the bearing formed by the bearing sleeve and the housing includes: a journal bearing for radially supporting the main shaft in a radial direction with respect to the bearing sleeve and the housing; And a thrust bearing portion for supporting the housing with static pressure in the thrust direction.

According to the first or second aspect of the present invention, the housing is formed of a metal material such as stainless steel having corrosion resistance, and the bearing sleeve is formed of a brittle material such as graphite having self-lubricating properties. A spindle suitable for an electrostatic coating machine using a conductive paint can be realized.

According to a fifth aspect of the present invention, when the specific gravity of the bearing sleeve is set to 1/3 or less of the specific gravity of the housing and the volume of the bearing sleeve is larger than that of the housing, the housing including the housing and the bearing sleeve is provided. This is preferable in that the weight of the entire assembly can be reduced.

If the air passage of the compressed air to be supplied to the journal bearing and the thrust bearing is formed in the bearing sleeve as in the invention of claim 6, the volume of the housing can be easily reduced. Is preferred.

The present invention is applicable to a structure in which a driving turbine section is formed integrally with the main shaft as described in claim 7, and the driving turbine section is formed as described in claim 8. It is preferable that the thrust bearing portion is formed and formed at the outer diameter of a thrust plate connected to the main shaft.

Also, the present invention is applicable to a structure in which the housing is elastically supported by a synthetic resin fixing member via an elastic member as described in claim 9. Furthermore, it is suitable when a water-soluble paint is used for the electrostatic coating machine as described in claim 10.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spindle for an electrostatic coating machine according to the present invention will be described in detail below. The same parts as those in FIG. 2 are denoted by the same reference numerals.

FIG. 1 shows an embodiment of a spindle 31 for an electrostatic coating machine using an air turbine as a driving means. The spindle 31 forms a drive turbine section 6 by providing a plurality of recesses 4 on the outer diameter of the thrust plate 3 of the main shaft 2, and the compressed air flows from a turbine nozzle 5 disposed at a portion facing the recesses 4. The main shaft 2 is rotated by spraying, and an atomizing head for atomizing the paint is attached to one end of the main shaft 2 (not shown).

The main shaft 2 and the thrust plate 3 integrally connected to the main shaft 2 are composed of journal bearings 42 and thrust bearings formed on bearing sleeves 37, 38 and first and second housings 39, 40. 43, 44, the bearing sleeves 37, 38 and the first and second housings 3
It is rotatably supported in a non-contact manner with respect to 9, 40.

The journal bearing portion 42 and the thrust bearing portion 43 are formed by shrink-fitting the bearing sleeve 37 to the substantially cylindrical first housing 39, and internally fitting the bearing sleeve 37 by appropriate means such as press-fitting or bonding. Similarly, the thrust bearing portion 44 is configured by shrink-fitting the bearing sleeve 38 into the second housing 40 having a circular lid shape and fitting the sleeve by appropriate means such as press-fitting or bonding.

A ring-shaped third housing 41 is interposed between the first and second housings 39 and 40, and the housings 39 to 41 are integrally assembled by fastening means such as bolts. These housings 39-4
Numeral 1 is housed in a resin coating machine case 19 (fixed member) via an elastic member 20 such as an O-ring. The housings 39 to 41 are formed of stainless steel as a metal material having corrosion resistance.

Thus, even when a water-soluble paint is used in the electrostatic coating, the corrosion of the housings 39 to 41 by the water-soluble paint can be suppressed. Also,
When the housings 39 to 41 are processed, deformation by the chuck is small, and high-precision processing of the bearing surface can be easily realized.

The bearing sleeves 37, 38 have a specific gravity of 1/3 or less of the stainless steel forming the housings 39 to 41, and are formed of graphite which is a brittle material having excellent self-lubricating properties. In both of them, a plurality of fine journal bearing nozzles 45 and 46 and thrust bearing nozzles 47 and 48 are provided.

Since the bearing sleeves 37 and 38 are formed of graphite, in the case of electrostatic coating using a water-soluble paint having a high viscosity, in order to improve the coating performance, it is necessary to realize a high-speed rotation of the spindle 31. The durability of the air bearing can be improved. The bearing sleeves 37, 3 made of graphite are used.
Since the first and second housings 39 and 40 in which the fitting 8 is fitted are made of stainless steel, no anodic corrosion occurs at the joint surface between them.

Here, a conventional spindle 1 (see FIG. 2)
Then, the air passage 2 is provided in the first and second housings 9 and 10.
1, 23 and the circumferential groove 25 were formed,
In the spindle 31 of this embodiment, the bearing sleeve 3
The air passages 51 and 55 are formed in 7, 38 (the conventional circumferential groove 25 is eliminated and the air passage 23 is shortened). As a result, the housings 39, 40 are connected to the bearing sleeves 37,
38, the housing 39 to
It is possible to reduce the weight of the entire housing assembly including the housing 41 and the bearing sleeves 37 and 38.

That is, air passages 51 and 55 are formed in the bearing sleeves 37 and 38 so as to communicate with the journal bearing nozzles 45 and 46 and the thrust bearing nozzles 47 and 48, respectively. Circumferential grooves 56 and 57 communicating with the air passages 51 and 55 are provided in the first and second housings 39 and 55, respectively.
40, and an air supply port 58 communicating with the circumferential groove 56 thereof.
Are provided in the first housing 39. Further, the air passage 29 communicating with the air supply port 58 is provided in the coating machine case 1.
9. A plurality of turbine nozzles 5 are formed in the third housing 41 so as to penetrate substantially in a tangential direction along the inner periphery of the thrust plate 3 at positions facing the recesses 4.

In the spindle 31 of this embodiment, the housings 39 to 41 are formed of, for example, stainless steel having a specific gravity of about 7.8, and the bearing sleeves 37 and 38 are formed of a specific gravity of about 2.
The bearing sleeves 37 and 38 with respect to the housings 39 to 41 have a volume ratio of 1 or more. With such a configuration, the conventional structure (see FIG. 2),
That is, the housings 9 to 11 are formed of an aluminum alloy having a specific gravity of 2.6 to 2.8, and the bearing sleeves 7 and 8 are formed of a copper-based alloy having a specific gravity of 6.5 to 9.0. The weight can be made equivalent to the case where the volume ratio of the housings 9 to 11 to 1 is 1 or more.

The compressed air supplied from the air passage 29 of the coating machine case 19 is supplied to an air supply port 58 of the first housing 39.
From the air passage 5 of the bearing sleeve 37 through the circumferential groove 56
1 and is jetted from the journal bearing nozzles 45 and 46 of the journal bearing portion 42 to the bearing surface, and the journal bearing portion 42 supports the main shaft 2 in the radial direction.

The compressed air supplied to the air passage 51 of the bearing sleeve 37 is jetted from the thrust bearing nozzle 47 to the bearing surface of the thrust bearing 43. Further, the compressed air is supplied to the first, third and second housings 39 and 4.
The air is supplied to the air passage 55 of the bearing sleeve 38 from the air passages 52, 54 and 53 of the bearing sleeve 38 via the circumferential groove 57.
It is jetted from the thrust bearing nozzle 48 to the bearing surface of the thrust bearing portion 44. Thus, the thrust bearing 43,
At 44, the main shaft 2 is supported in the axial direction.

On the other hand, the compressed air supplied from the air passage 30 of the coating machine case 19 is ejected from the turbine nozzle 5 of the third housing 41 toward the recess 4 of the thrust plate 3 of the main shaft 2 in a substantially tangential direction. . The jetted compressed air gives a rotational force to the main shaft 2 and is discharged to the outside of the spindle 31 from an exhaust port (not shown). An atomizing head (not shown) for atomizing the paint is attached to an end (the left end in the figure) of the main shaft 2 to perform electrostatic coating.

[0038]

According to the present invention, the housing is formed of a metal material such as stainless steel having corrosion resistance, and the bearing sleeve is formed of a brittle material such as graphite having self-lubricating properties. It is possible to provide a spindle which is suitable for use in an electrostatic coating machine that uses, is excellent in corrosion resistance and bearing durability when used at high speed rotation, and is easy to realize weight reduction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a spindle for an electrostatic coating machine according to the present invention.

FIG. 2 is a sectional view showing a conventional example of a spindle for an electrostatic coating machine.

[Explanation of symbols]

 2 Main shaft 3 Thrust plate 6 Drive turbine section 19 Fixing member (coating machine case) 20 Elastic member 37, 38 Bearing sleeve 39-41 Housing 42 (Journal) bearing section 43, 44 (Thrust) bearing section 51, 55 Air passage

Claims (10)

[Claims] 1. A main shaft, a bearing sleeve constituting a bearing portion for rotatably supporting the main shaft in a static pressure, and a housing externally fitted to the bearing sleeve, wherein paint is atomized on one end of the main shaft. The bearing sleeve is formed of a brittle material having self-lubricating properties, and the housing is formed of a metal material having corrosion resistance. Spindle for electrostatic coating machine. 2. A bearing formed by the bearing sleeve and the housing, a journal bearing for radially and statically supporting the main shaft in the bearing sleeve and the housing, and a journal bearing in the bearing sleeve and the housing. 2. The spindle for an electrostatic coating machine according to claim 1, further comprising a thrust bearing portion for supporting a static pressure in a thrust direction. 3. The spindle for an electrostatic coating machine according to claim 1, wherein the brittle material is graphite. 4. The spindle according to claim 1, wherein the metal material is stainless steel. 5. The bearing according to claim 1, wherein the specific gravity of the bearing sleeve is set to 1/3 or less of the specific gravity of the housing, and the volume of the bearing sleeve is larger than that of the housing. Spindle for electrostatic coating machine. 6. The electrostatic coating machine according to claim 1, wherein an air passage for compressed air supplied to said journal bearing and said thrust bearing is formed in said bearing sleeve. spindle. 7. The spindle for an electrostatic coating machine according to claim 1, wherein a driving turbine section is formed integrally with said main shaft. 8. The electrostatic coating machine according to claim 7, wherein the drive turbine portion forms a thrust bearing portion and is formed at an outer diameter of a thrust plate connected to the main shaft. For spindle. 9. The spindle for an electrostatic coating machine according to claim 1, wherein said housing is elastically supported by a synthetic resin fixing member via an elastic member. 10. The spindle for an electrostatic coating machine according to claim 1, wherein a water-soluble paint is used for said electrostatic coating machine.